Filoviruses, like Ebolavirus, are category A infectious agents that cause disease with rapid onset and high mortality. To date, no approved vaccine or drug therapy is available for any filovirus. Therefore, all work requires the highest level of biological containment. This has hampered efforts to understand their unusual infection mechanism and develop a therapy. The main barrier against development of a useful therapy is the high level of genome sequence diversity seen in the filovirus superfamily. This means that a vaccine will probably only protect against a limited number of virus isolates. However, the filoviruses share common features of entry mechanism into cells and so, a drug that interferes with the entry step has a high chance of broadly inhibiting many virus isolates. In this project we take advantage of the outcome of our screening of 350,000 compounds from the MLPCN chemical library. The work was done in collaboration with Dr. Simeonov's team at NCATS. Following up from the screen, we found that 75% of hits against wild type Marburgvirus also inhibit infection by Zaire Ebolavirus. This means that a broad-spectrum anti-filovirus drug is possible. We also found 5 distinct classes of chemical scaffold were active. In the proposed project we will examine two compounds from each group to: 1) determine if each is active against representative Ebolaviruses from each of the major virus families, 2) determine if compounds protect human primary cell types that are relevant targets of virus infection 3) determine the mechanism of virus infection inhibition for steps of cell entry. This work draws upon our expertise in understanding filovirus entry mechanism and will extend our collaboration with the NCATS team. The work will promote the best candidate class of compounds for future development through clinical chemistry at NCATS and animal testing toward creating a useful broad-spectrum anti-filovirus drug therapy.